punypng is a free png compression service that intelligently leverages multiple open-source png compression algorithms in the hopes of making the web more puny, one png at a time. It handles 8-bit PNGs, 24-bit PNGs, JPEGs, GIFs and animated GIFs. It also leverages dirty transparency techniques to further optimize transparent images beyond what typical compressors like pngcrush can handle.
- Clear affordances for # of bytes saved (as well as being pretty bar graphs)
- JPEGs are analyzed to see if a compressed PNG format’s better (ex: JPEGs with heavy solid areas benefit from this). But if not, don’t despair, punypng is backed with jpeg-tran and jpegoptim for further JPEG optimzation.
- You can upload up to 50 files in a single session.
- Download batch jobs as a single time-stamped ZIP.
More info: punypng